1. Field of the Invention
The present invention relates to a thin optical lens assembly, and more particularly to a compact thin optical lens assembly applied to an electronic product.
2. Description of the Related Art
As science and technology advance, the development of electronic products such as miniaturized or thin digital still cameras, web cameras or mobile phones tends to have a compact design to meet the market demands, along with features of high resolution and high image quality.
In general, a conventional optical lens assembly of a compact electronic product comes with different designs, including the two-lens, three-lens, four-lens, and five-or-more lens designs. If the cost is taken into considerations, the two-lens design adopts a smaller number of lenses and is able to offer a lower selling price. In the lenses of a compact digital camera, web camera or mobile phone, the optical system requires a compact design, a short focal length and a good aberration adjustment. With a first lens element with a positive refractive power, a second lens element with a positive refractive power, or other combination as disclosed in U.S. patents and publications of U.S. Pat. Nos. 7,110,190, 7,088,528 and US2004/0160680, European Pat. No. EP1793252, Japanese Pat. Publication Nos. JP2007-156031 and JP2006-154517, R.O.C. Pat. Nos. TWM320680, TWM350713 and TWI232325, and P.R.C. Pat. No. CN101046544, the requirements for a compact design can be met. However, the optical systems disclosed in these patents further reduce the total length of the lens to meet the demands for a compact design. As disclosed in U.S. Pat. No. US2006/0221467, Japan Pat. Nos. JP2005121685, JP2006154517, and JP20040281830, and R.O.C. Pat. Publication No. TW201015137, a combination of positive-negative or negative-positive refractive power arrangements is adopted to reduce the length of the lens. Although these patented technologies adopting a direct way of shortening the focal length can reduce the total length of the lens effectively, it is difficult to adjust the focus, and correct or reduce the pronounced aberrations or image distortions. Therefore, the present invention provides a feasible design for shortening the total length of the optical system with a more advantageous combination of refractive power and surface curvature properties of two lens elements to reduce the total length of the optical system effectively while improving the image quality for designs applied to compact electronic products.